Liners provide a soft, flexible interface between a residual limb of an amputee and a hard socket to which a prosthetic device is secured. Such liners are typically made of an elastomer material such as silicone. Such liners may also be used in connection with orthotic devices. Prosthetic suspension liners are described in prior patents, and may be fabricated of elastomer or rubber materials, and are used to cushion a post-operative stump or residual limb with respect to a prosthesis that is installed over the residual limb and coupled to the liner, e.g. by a conventional locking device.
Such liners should conform closely with the residual limb, accommodate all surface contours and sub-surface bone elements of the residual limb, and provide a comfortable cushion between the residual limb and the hard socket of the prosthesis that is to be fitted over the residual limb. Various silicone rubber or elastomer materials are used for suspension liners. Such elastomer materials having an appropriate hardness/softness, elongation, tensile, and other properties, such as bio-inertness (resulting in no skin reaction), have been successfully used for suspension liners.
The elastomer forming the liner frictionally engages and remains attached to the skin of a residual limb so that the limb is retained within the prosthetic socket in a comfortable, non-irritating manner. For example, liners may be used for any level of amputation both upper and lower limb. Prosthetic liners are used to cushion the amputee's residual limb from shock during ambulation.
Amputee limb heath is an important factor in prosthetic liner choice. During normal ambulation the residual limb can produce perspiration that accumulates in the distal end of the liner. With the advent of vacuum assisted or suction socket systems the residual limb is surrounded in a non-permeable material that may trap perspiration or air against the skin, this environment may be detrimental to limb health.
Another consequence of moisture or air against the residual limb is the possibility of losing the link between the liner and skin. A loss of linkage could result in the detachment or loss of the prosthesis.